Laterally diffused metal oxide semiconductor (LDMOS) devices are used in power application devices because they complement both bipolar devices and complementary metal-oxide-semiconductor CMOS devices through bi-polar-CMOS-DMOS (BCD) processes. For example, LDMOS devices may be used in radio frequency amplifier devices and microwave power amplifier devices to furnish power application functionality. LDMOS devices rely on a shallow conduction layer formed under a LOCOS (“local oxidation of silicon”) region or a STI (shallow trench isolation) region to handle the higher drain voltage, when the device is biased.
The on-state resistance (“RON”) and the maximum breakdown voltage (“BVDSS”) of the device are two important characteristics of LDMOS designs. Gate resistance (Rg) is another important LDMOS characteristic that affects the frequency performance of the LDMOS. All three characteristics are important for the operating parameters for the LDMOS devices, which dictate the applications with which the devices may be utilized. On-state resistance is usually dependent upon the design/layout of the device, the process condition, temperature, diffusion length, and the various materials used to fabricate the devices. Breakdown voltage is defined as the largest reverse voltage that can be applied to a diode (e.g., a p-n junction) without causing an exponential increase in the current of the diode. Gate resistance is dependent upon the dopant and the silicoidation in the polysilicon gate and how the wiring metal (1st metal or 2nd metal) is connected to the polysilicon.